Tape recording and reproducing apparatus



Jan. 3, 1967 w. "r. SELSTED ET AL 3,295,780

TAPE RECORDING AND REPRODUCING APPARATUS Original Filed Nov. 29, 1963INVENTORS WALTER T. SELSTED WILLIAM 1. GIRDNER BY 62 0w United StatesPatent 3 Claims. (Cl. 242-5512 This is a divisional application of ourapplication serial number 326,811 entitled Tape Recording andReproducing Apparatus, filed November 29, 1963.

This invention relates to improved tape recording and reproducingapparatus.

It is an object of the present invention to provide an improved brakingsystem for the tape reels of tape recording and reproducing apparatus.

Other and incidental objects of the present invention will be apparentfrom a reading of this specification and an inspection of theaccompanying drawing which shows a top view of the tape recording andreproducing apparatus showing the location of components on the baseplate.

Referring now to the drawing, the tape recording and reproducingapparatus is shown assembled on base plate 9. The tape 11 from supplyreel 13 follows a path around guide 15, roller 17, guide 19 mounted onrotatable arm 21, the flywheel roller 23 and through the assembly ofsignal transducer heads 25. The tape 11 is pulled through this path bythe capstan drive which includes the capstan shaft 27 and pinch roller29. The tape 11 then follows the path around guide 31 mounted onrotatable arm 33 to the takeup reel 35. The supply reel 13 is mounted onthe rotatable shaft 37 of 'motor 77. The brakeband 45 which has both ofits ends mounted on a pivotal arm 47 is disposed around substantiallythe entire periphery of brakedrum 41. The pivotal arm 47 is actuated byspring 111 when the holdoif solenoid 53 is deenergized. A similar brakemechanism including brakeband 49 having its both ends mounted on pivotalarm 51 and disposed around substantially the entire periphery ofbrakedrum 43 is provided for takeup reel 35. This brake is actuated byspring 113 when solenoid 53 is deenergized. The pinch roller 29 mountedon rotatable arm 55 and tape guide 19 mounted on rotatable arm 21 areactuated by solenoid 57. A footage counter 59 is mechanically drivenfrom the roller 17 and thus provides an indication of the number of feetof tape 11 passing over roller 17 The supply reel 13 and takeup reel 35are each attached to brakedrums 41, 43 mounted on the shafts 37, 39 ordrive motors 77, 91 associated with each of the reels, as shown inFIGURE 1. The brake mechanisms are held in the inoperative condition bythe solenoid 53 through connecting linkages 107 and 169. When thesolenoid 53 is deenergized, the brakes are pulled into engagement withbrakedrums 41, 43 by springs 111, 113. Both ends of the brake bands 45,49 are connected to lever arms 47, 51 at different arm lengths about thepivots, thereby providing braking torques which are substantiallyindependent of changes in the coefficient of friction between the drumsurfaces and the brake bands and which are greater in one rotationdirection than in the other rotation direction. This is because anincrease in the coeflicient of braking friction causes an increase inthe force exerted on the spring through the lever arm as a result of thepull exerted on the brake band in the direction of rotation. As thespring stretches, the brake band unwraps from the brake drum, therebycompensating for the increase in braking friction. Conversely, if

the braking friction decreases, less stretching force is exerted on thespring and the brake band thus wraps more tightly around the brake drum.The product of the coeflicient of braking friction and the force withwhich the brake band is urged against the brake drum thus remainssubstantially constant.

The braking torque is greater in one rotation direction than in theother direction because of the dissimilar lever arm distances throughwhich the spring exerts force on the ends of the brake bands. It can beseen that the spring force exerted on the end of brake band 45 which ispulled by counterclockwise rotation of brake drum 41 is multiplied bythe ratio of lever arm distances about the pivot while the spring forceexerted on the end which is pulled by clockwise rotation of the brakedrum 41 is substantially the spring force itself. A similar brakemechanism including brake drum 43 and brake band 49 is provided for thetakeup reel 35 and is arranged to produce the greater braking torque ina rotation direction which is opposite to that direction for which thesupply reel brake mechanism produces the greater braking torque. Brakesarranged in this manner tend to enable the reel from which tape isunwinding to decelerate more rapidly than the remaining reel, therebymaintaining tension on the tape. Also brakes arranged in this mannereliminate the backlash commonly encountered in conventional brakemechanisms following reversal of the direction of braking or followinginitial engagement of the brake band and brake drum.

We claim: 1. In tape recording and reproducing apparatus having a reelof tape, braking means for said reel comprising:

a brake drum disposed to rotate with said reel; a brake band disposedabout a portion of the periphery of said drum; a pivoted arm; meansattaching the ends of said band to said arm at dissimilar distances fromsaid axis at locations and at locations thereon which move both ends ofsaid band in band-tightening directions about said drum in response torotation of said arm in a selected direction about said pivot axis; andmeans to rotate said arm in said selected direction about the pivotthereof for actuating said braking means. 2. In tape recording andreproducing apparatus having a reel of tape, braking means for said reelcomprising:

a brake drum disposed to rotate with said reel; a brake band disposedabout a portion of the periphery of said drum; an arm pivotable about anaxis; means attaching the ends of said band to said arm at dissimilardistances from said axis at locations thereon which move both ends ofsaid band in bandtightening directions about said drum in response torotation of said arm in a selected direction about said pivot axis;means urging said arm in said selected direction to tighten the bandabout said drum; and means attached to said arm for urging said arm in adirection to move the ends of said band in bandexpanding directionsabout said drum. 3. In tape recording and reproducing apparatus having atape supply reel and a takeup reel, braking means for said reelscomprising:

a brake drum for each of said reels disposed to rotate therewith; andfor each of said brake drums, a brake band disposed about a portion ofthe periphery of said drum; an arm pivotable about an axis; meansattaching the ends of said band to said arm at dissimilar distances fromthe pivot axis of said arm 3 4 and at locations thereon which more bothends of means attached to said arms for simultaneously urging 831d bandin band-tightening directlons about Said said arms in directions to movethe ends of said drum 1n ffisponse to Totatlon of Sald arm m a bands inband-expanding direction about said drums.

lected direction about-said pivot axis;

means urging said arm in said selected direction to 5 tighten the bandabout said drum; References Cited by the Examiner the braking means foreach reel providing greater UNITED STATES PATENTS brakmg torque in onedlrection of drum rotation 2,781,186 2/1957 Harbers et a1 X than in theopposite direction;

the braking means for one reel being disposed to exert 10 3,075,7161/1963 Morgan 242' 55-12 greater braking torque in a direction of drumrotation opposite to the direction of drum rotation in FRANK J. COHEN,Primary Examiner. which the braking means for the other reel exerts thegreater braking torque; and LEONARD D. CHRISTIAN, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No Q 3,295,780 January 3, 1967 Walter T. Selsted et al.

in the above numbered pattified that error appears rs Patent should readas It is hereby oer ent requiring correction and that the said Lettecorrected below.

strike out "said axis at locations,

Column 2, line 38,

f said arm and insert instead the'pivot axis 0 Signed and sealed this26th"day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Commissioner of Patents AttestingOfficer

1. IN TAPE RECORDING AND REPRODUCING APPARATUS HAVING A REEL OF TAPE,BRAKING MEANS FOR SAID REEL COMPRISING: A BRAKE DRUM DISPOSED TO ROTATEWITH SAID REEL; A BRAKE BAND DISPOSED ABOUT A PORTION OF THE PERIPHERYOF SAID DRUM; A PIVOTED ARM; MEANS ATTACHING THE ENDS OF SAID BAND TOSAID ARM AT DISSIMILAR DISTANCES FROM SAID AXIS AT LOCATIONS AND ATLOCATIONS THEREON WHICH MOVE BOTH ENDS OF SAID BAND IN BAND-TIGHTENINGDIRECTIONS ABOUT SAID DRUM IN RESPONSE TO ROTATION OF SAID ARM IN ASELECTED DIRECTION ABOUT SAID PIVOT AXIS; AND MEANS TO ROTATE SAID ARMIN SAID SELECTED DIRECTION ABOUT THE PIVOT THEREOF FOR ACTUATING SAIDBRAKING MEANS.